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Ray Tensing faces a murder charge for the fatal shooting of Sam DuBose

If convicted, Ray Tensing faces life in prison

(CNN)What should have been a minor traffic stop led to the death of an unarmed Ohio father of 13.

On July 19, 2015, University of Cincinnati Police Officer Ray Tensing pulled over 43-year-old Sam Dubose because of an allegedly missing front plate.

Tensing fatally shot Dubose after a tussle that was captured on the officer's body camera. He was fired from his job, arrested and indicted on murder and voluntary manslaughter charges. He was released from custody after posting a tenth of his $1 million bond.

More than a year after pleading not guilty, Tensing's trial is set to begin Tuesday -- but not without some last-minute controversy. Here's what you need to know ahead of opening statements.

After making the July 19 stop, Tensing asked DuBose for his license, which was suspended. When DuBose couldn't find it, Tensing grew frustrated and asked the motorist to undo his seat belt.

Tensing, a 26-year-old officer with five years' experience, tried to open the Honda Accord's door. But DuBose held it shut. After that, Tensing reached into the car-- and at that moment, his body camera shook out of focus.

"Shot fired! Shot fired!" someone yelled moments later.

DuBose's car rolled for about a block before crashing. He later died.

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The death of DuBose, who was black, happened in the same yearlong period that saw several controversial officer-involved shootings -- including those of Tamir Rice in Cleveland, Michael Brown in Ferguson, Missouri, and Walter Scott in North Charleston, South Carolina.

What does Tensing say about the stop?

Tensing said he had to fire his weapon after nearly being run over. Tensing noted that his hand had gotten caught in DuBose's car. "I think I'm OK," Tensing can be heard saying in the video. "He was just dragging me. I thought I was going to get run over. I was trying to stop him."

Tensing left the scene with another officer to get his hand checked out. The footage shows no one rendering aid to DuBose.

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"I know when you're supposed to use deadly force: You're supposed to use it when you have reasonable fear of great bodily injury," said Mark O'Mara, an attorney for the DuBose family. "There was none of that."

Tensing's attorney believes he feared for his life.

Did the video clear things up?

Not much. It's hard to see what happens in key parts of the footage.

It wasn't long before Tensing pulled out his gun -- though it's hard to hear the gunshot. There's a bang, but the camera shakes so much that viewers are unable to clearly see the shooting.

The video eventually shows Tensing holding the gun in front of his chest after the car has moved away.

What's happened since then?

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It didn't take long for Tensing to lose his job and face an indictment for murder.

At the time, Hamilton County Prosecutor Joe Deters called the shooting "the most asinine act I've ever seen a police officer make" in decades.

The University of Cincinnati later commissioned an independent review that found Tensing had led his police department in the number of stops and citations, as well as the racial disparity among those stopped.

Earlier this year, the University of Cincinnati agreed to pay nearly $4.85 million to the DuBose family, provide free undergraduate education to his 13 children, invite the family to take part in meetings on police reform and issue a formal apology, a press release from the family said.